Bill Maher: Republican Party a Bunch of 'Religious Lunatics, Flat-Eathers and Civil War Reenactors' (VIDEO)

Bill Maher and Bill O'Reilly squared off on the state of conservatism in America on Wednesday night's 'The O'Reilly Factor' (weekdays, 8 PM ET on Fox News.)

O'Reilly began the segment by telling Maher that he remembered that Maher used to be a lot less liberal. Maher agreed, but said that wasn't because his political philosophy shifted, but rather because "the left moved to the center and the right moved into a mental institution."

"There used to be ideological differences that were understandable," Maher explained. "That has gone away."

"The Republican party now is just a bunch of religious lunatics, flat-earthers and Civil War reenactors,' Maher continued, making O'Reilly laugh with his characterization. "So I don't think it was me who changed so much."